Batteries and Renewable Energy Set to Grow Together

POMONA, Calif. — The future of American energy, according to one widely held view, will include solar panels and wind turbines continuing to proliferate, churning out ever more electricity and eventually eclipsing fossil fuels to help offset the forces of climate change.

With the cost of renewable technologies falling sharply, that vision is starting to take shape, especially in areas with abundant sunshine or steady wind. Here in California, the state is making such quick progress toward its goal of getting 33 percent of its electricity from renewable sources by 2020 that Gov. Jerry Brown raised the ante earlier this year, setting a target of 50 percent by 2030.

The shift sounds simple in theory — plug more solar and wind into the mix, and unplug more coal- or gas-burning power plants, sparing the world millions of tons of greenhouse gases.

But the reality is more complex. Because of the variable nature of these renewable sources — no electricity is generated when the sun goes down or the air is still — they add strains to the system of transmitting and distributing power.